Room-Temperature Flexible CNT/Fe2O3 Film Sensor for ppb-Level H2S Detection.

Carbon nanotubes (CNTs) had room temperature response, large surface area, and excellent mechanical properties, making them favorable for the design of flexible, wearable, and portable gas sensors. However, CNTs were lacking in response and selective response to different gases, such as H2S. Here, we demonstrated a flexible H2S ppb-level gas sensor based on a carbon nanotube/amorphous Fe2O3 (CNT/Fe2O3) film at room temperature, which was fabricated via a simple one-step solvent-thermal method. The CNT/Fe2O3 film gas sensor exhibited a high selective response to H2S (with a response of 55.1% to 100 ppb H2S), rapid reversible response at room temperature (with a response time of ∼127 s to 100 ppb H2S), and low limit of detection to about 2 ppb. Additionally, the CNT/Fe2O3 film maintained good sensing performance under various bending conditions and could be further fabricated into the fiber gas sensor device via wet stretching, retaining response at the ppb level (with a response of 18.6% to 100 ppb H2S). This research on a flexible gas sensor device based on the CNT film/fiber opened up new possibilities for wearable portable electronic device applications.

Integrated Catalyst-Substrate Electrodes for Electrochemical Water Splitting: A Review on Dimensional Engineering Strategy.

Water splitting (or, water electrolysis) is considered as a promising approach to produce green hydrogen and relieve the ever-increasing energy consumption as well as the accompanied environmental impact. Development of high-efficiency, low-cost practical water-splitting systems demands elegant design and fabrication of catalyst-loaded electrodes with both high activity and long-life time. To this end, dimensional engineering strategies, which effectively tune the microstructure and activity of electrodes as well as the electrochemical kinetics, play an important role and have been extensively reported over the past years. Here, a type of most investigated electrode configurations is reviewed, combining particulate catalysts with 3D porous substrates (aerogels, metal foams, hydrogels, etc.), which offer special advantages in the field of water splitting. It is analyzed the design principles, structural and interfacial characteristics, and performance of particle-3D substrate electrode systems including overpotential, cycle life, and the underlying mechanism toward improved catalytic properties. In particular, it is also categorized the catalysts as different dimensional particles, and show the importance of building hybrid composite electrodes by dimensional control and engineering. Finally, present challenges and possible research directions toward low-cost high-efficiency water splitting and hydrogen production is discussed.

Recent Advances in MXene-Based Fibers: Fabrication, Performance, and Application.

Two-dimensional transition metal carbide/nitrides (MXenes) have recently received extensive attention due to their diverse material types and versatile structures, large-scale production, and excellent properties. MXene sheets possess abundant hydrophilic functional groups on their surface, which enable them to be assembled into macroscopic fibers or compounded with other functional materials to produce composite fibers. This review aims to provide a comprehensive analysis of MXene fibers in terms of their fabrication, structure, properties, and recent applications as flexible and wearable electronics. The review will discuss the principles of different methods used to synthesize MXene fibers and analyze the characteristics of the as-synthesized fibers, with a particular focus on the wet spinning method. The fundamental relationships between the microstructure of MXene fibers and their resulting mechanical and electrical properties will be explored. Furthermore, the review will elaborate on the progress made in MXene-based fibers in the rapidly growing field of wearable electronics applications, provide insights into future development of MXene fiber materials and propose solutions to the challenges facing practical applications.

Carbon Nanotube-Coupled Seaweed-like Cobalt Sulfide as a Dual-Functional Catalyst for Overall Water Splitting.

Preparation of high-efficiency dual-functional catalysts remains the bottleneck for electrochemical water splitting. To prepare a non-precious metal catalyst with high activity and stability, here, we present a seaweed-like structure consisting of transition-metal sulfide nanoplates self-assembled on carbon nanotube sponge networks (SW-CoS@CNT). By adjusting the key parameters during synthesis (e.g., the loading amount and ratio of Co and S precursors), the microstructure can be tailored in a wide range, and sulfur defects can be introduced into the nanoplates by thermal annealing. The resulting SW-CoS@CNT serves as a freestanding dual-functional catalytic electrode, showing low overpotentials of 105 and 218 mV for the hydrogen evolution reaction and the oxygen evolution reaction, respectively, which are superior to most reported transition-metal-sulfide-based catalysts in alkaline solution. Rational design of this hierarchical biomimetic structure may be useful in developing high-performance electrochemical catalysts in renewable energy and environmental fields.

Engineering white light-emitting diodes with high color rendering index from biomass carbonized polymer dots.

Carbonized polymer dots (CPDs) have promise in the fields of sensing, bioimaging, and optoelectronic devices due to their excellent optical properties, favorable biocompatibility, and superior stability. Biomass CPDs present greater advantages in terms of their lack of toxicity, low cost, easy preparation, and feasibility in terms of luminescence-related applications. Here, two kinds of fluorescent CPDs were obtained through the simple hydrothermal method using biomass avocado peel (CPDs-P) and sarcocarp (CPDs-S) as carbon sources. Interestingly, these two biomass CPDs have excellent applications in ion detection and light-emitting diodes (LEDs). Analysis and results show that CPDs-P possess better sensitivity to Fe3+ because they have more oxygen-containing functional groups. After mixing with epoxy resin, warm and cold white LEDs with CIE (Commission Internationale de L 'Eclairage) coordinates (0.38, 0.39) and (0.29, 0.34) were constructed successfully from extremely stable CPDs-P and CPDs-S. The high color rendering index of the prepared white LEDs are 90.47 and 84.54. This study shows that these biomass CPDs are promising materials in sensing and white LEDs illumination.